Articulated mandrel for cross rolling mills



April 1941- s. E. DIESCHER 2,239,085

ARTICULATEIS MANDREL FOR CROSS ROLLING MILLS Filed Dec. 17, 1938 2 Sheets-Sheet 1 IN VENTOR.

ATTORN Y: I

April 22, 1941. s. E. DI'ESCHER 2,239,035

ARTICULATED MANDRELL FOR CROSS ROLLING MILLS Filed Dec. 17, 1938 2 Sheets-Sheet 2 F IG. 2.

' INVENTOR.

4;, ATTORNEYS.

, Patented Apr. 22, 1941 ARTICULATED MANDREL FOR CROSS ROLLING MILLS V Samuel E. Diescher, Pittsburgh, Pa., assignor to Diescher Tube Mills, Inc., Pittsburgh, Pa., a corporation of Delaware Application December 17, 1938, Serial No. 246,346

4 Claims.

The invention relates to mandrels 'for use in cross rolling mills of the driven guide disc type when such mills are operated to elongate tubular blanks and simultaneously to reduce the wall of each to two or more normal and to an intermediate heavy internal upset thickness.

A driven guide disc cross rolling mill of the type herein contemplated is disclosed in my United States Patent No. 1,870,209, in the operation of which a pierced or otherwise formed tubular blank is cross rolled upon a cylindrical mandrel to reduce the wall thickness and elongate the blank. Between the cross rolls, above and below the pass line, there is positioned a pair of guide discs that are driven at, a peripheral speed in excess of the speed of longitudinal movement of the blank effected by the cross rolls,

the guide discs being eifective to limit the lateral bulgin or ovalling of the blank, to divert such thickness that its interior circumference is less than that of the large diameter portions of the mandrels, herein designated as a heavy upset, because it is characteristic of the operation of cross rolling mills of the type explained above that while being formed a tubular blank moves forwardly at a speed in excess of that of the mandrel on which it is formed. Accordingly, if an interior upset is such that it will not pass over the large diameter portion of the mandrel, or, in other words, if it is a heavy upset, the upset will engage the transition portion of the mandrel with the result that the metal of the tube at the rear of the upset will, if it is not sufficiently rcsistant, become buckled or otherwise distorted by reason of the forward feeding action of the guide discs. and the tube will accordingly be de stroyed, or will, if it is sufficiently resistant to --avoid injury, cause the mandrel to accelerate in its forward movement and thus not only require the mandrel to be longer than necessary but also requile more powerto be consumed in the rolling of the workpiece.

The object of this invention is to provide a longitudinally the eri heral flow of the metal :0 mandrel f us i a cross rolling ll f the ty of the blank, and to pull the metal of the blank xplained, he mandrel being so constructed forwardly at a rate of advance exceeding that hat Seamless tubes m y Without prejudicial 0 of the mandrel within the blank. sequences, be provided with heavy intermediate 'In my patent application Serial No. 239,211, upsets during the wall reduction and elongation filed November '7, 1938, there is disclosed a meth- .2", of ubular blanks. 0d, capable of being performed by the mill dis- The invention is illustrated in the accompanyclosed in my above mentioned patent, of prog draw ngs, of which Fig. 1 is a face view of viding seamless tubing with interior upsets simulan artiwlated mandrel embo y n the inventaneously with the reduction of wall thickness t on, a portion of it being Shown in ud and elongating of tubular blanks. The term up- ;y; nal central section; Fig, 2 a vertical central secset is there, and here, used to designate that tional view through the upper half of a cross portion of a tube whose wall is thicker than the rolling 'mill of the type herein fl e p a ed 00 normal wall thickness. According to the method bined with a horizontal central sectional view of disclosed in that application, seamless tubular a at half of the mill, in the pa f w h blanks may be reduced in wall thickness and mill a po f t m n el of Fig. 1, and of elongated and simultaneously provided with upa work pie Surrounding e shown at the sets at one or both of their ends, as .well as interbeginning of the formation of an intermediate mediate of their ends. or with both end and interupset on the work piece; Fig. 3 a view the same .mediate upsets. The position and size, both as Fig. 2 with the exception that the action of length and wall thickness, of the upsets are de 4:) the mill is shown at the end of the formation termined lar ely by the mandrels that are used; of the upset: and Fig. 4 a view the same as Figs. They are provided with large like diameter work- 2 and 3 with the exception that the action of ing face portions for determining the normal wall the mill is shown after the upset has passed bethickness of the, tubes, and with smaller diameyond the mill. In Figs. 2, 3 and 4 the configurater wor ing face portions for determining the up- 4;) tion of the'work piece is shown in somewhat exsets. aggerated forms.

In the use of unitary mandrels and of a cor- In the practice of this invention I provide an rect rollin procedure, such as disclosed in my articulated mandrel formed of two or more parts said application, it is impossible to provide a which are readily separable, the number of parts seamless tube with an intermediate upset of 54) depending upon the number of intermediate heavy upsets it is desired to provide on the interior of a seamless tube. When the mandrel is in its assembled form in the bore of a work piece at the beginning of a reducing, elongating and upsetting operation, its working face consists of two or more spaced cylindrical portions of like diameter, which portions, in cooperation a tapered portion extending to the adjacent large diameter portion. The articulation of the mandrel, or in other words its division into separable sections, is such that one of each of its transition portions is borne by one of each of a pair of separable adjacent sections so that as the guide discs feed the metal of a tube forwardly the forward end of an upset may engage the transition portion on the leadin section of the mandrel and cause such section to travel forwardly more rapidly than the adjacent trailing section. u

The particular mandrel shown in Fig. 1 is formed in three sections l, 2 and 3 provided, respectively, with large diameter portions 4, 5 and 6, andpetween the successive large diameter portions 'there are small diameter portions 1 and 8.

Extending from adjacent large diameter portions to each small diameter portion there are tapered transition sections 9 and I0. To align the sections of the mandrel when assembled, and also to facilitate the removal of a mandrel from a tube after it has been formed, one section is provided with a central longitudinally extending socket II and the other with a correspondingly positioned pin l2 adapted to be received by the socket. These pins and sockets, or equivalent aligning instrumentalities, may be variously located along each small diameter portion of the mandrel or at one of its ends, provided always that one of each of a pair of adjacent transition portions 9 and I0 is formed on each of the adjacent mandrel sections. Preferably the outer end 'of the pin is tapered or rounded and the outer end of the socket flared outwardly, as shown, to. facilitate the centering of the pin in the socket when assembling the sections of a mandrel and when removing a mandrel from a formed tube.

The action of the articulated mandrel, and of a mill of the type herein contemplated, in the formation of an upset in the reduction and elongation of a tubular blank is shown in Figs.

3 and 4. The mill comprises a pair of cross rolls l5 which may be of any desired type, those shown being of the barrel type. Positioned between the cross rolls there is a pair of driven guide discs l6 provided with peripheral grooves. In the pass of the mill there are illustrated adjacent ends of sections of an articulated mandrel, which for example may be sections I and 2 of the mandrel of Fig. 1. Surrounding the mandrel at the entering-side of the mill there is a portion of an unreduced work piece l1, and similarly at the delivery side of the mill there is a portion of a reduced and elongated tube l8 surrounding section! of the mandrel In the throat of the pass shown in Fig. 2 the cross rolls are illustrated as cooperating with the transition portion 9 of the mandr l at the beginning of the formation of an inte ior upset on small diameter portion 1 At this transition portion the cross rolls effect a gradually diminishing reduction of the wall thickness of the blank as compared with that effected while the cross rolls cooperate with the large diameter portion Lot the mandrel, and throughout the formation of the upset on the small diameter portion the cross rolls effect a materially less reduction in wall thickness than effected when the cross rolls cooperate with the large diameter portion of the mandrel.

As has been explained, it is characteristic of the guide disc type of cross rolling mills that the driven guide discs feed the metal of a blank forwardly at a rate of speed exceeding that of the forward movement of the mandrel. Because of this, at the completion of the formation of an upset the length of the upset is greater than that tion portion 9 would buckle, become expanded or otherwise become impaired by reason of the forwardly feeding action of the guide discs, or, if no such injury resulted, then from that position where the upset was formed and during all of the remaining travel of the work piece through the pass the forward movement of the mandrel would occur at the same speed as that of the outgoing work piece. This increase in the rate of travel of the leading section is further illustrated in' Fig. 4, which shows the cross rolls and guide discs cooperating with the large diameter portion of the trailing section of the mandrel. in the reduction of blank II to the normal wall thickness desired.

To maintain the sections of a mandrel in their aligned positions with their joints closed until the Joints pass through the throat of the pass, forward feeding pressure may be applied to the rear of themandrel, as'for example by mandrel feeding or controlling mechanism such as disclosed in Patent No. 2,006,336 to A. P. Diescher.

When an upset tube has been thus formed, the next step in the operation is the removal of the articulated mandrel from the tube. It the formed tube is provided with a single intermediate upset by the use of a mandrel formed in two sections, the forward section may be withdrawn from the front and the rearward section from the rear end of the tube.- On the other hand, if the formed tube is provided with two or more intermediate upsets it is necessary toapply such pressure to one end of the mandrel, while the opposite end of the tube is held against an abutment, that the larger diameter portion or portions of the man- 4 drel will pass through the upsets. When that is done, a portion of the upsets appear as enlargements of the outer diameter of the tube. Apparatus for thus extracting mandrels from tubes provided with interior heavy upsets is illustrated and described in my above mentioned patent application Serial No. 239,211, as is also apparatus for subsequent treatment of upset tubes to cause the upsets to be either of the interior or exterior type. Because such apparatus forms no part of my present invention, it is not'herein illustrated.

The mandrel herein provided makes it possible to provide seamless tubes with heavy interior upsets simultaneously with the wall reduction and elongation of tubular blanks by mills oi the driven guide disc type.

According to the provisions of the patent statutes, I have explained the principle and operation of my. invention, and have illustrated and described what I now consider to be its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a mill for elongating heated tubular blanks and simultaneously reducing the wall of each principally to a normal and locally to an upset thickness, the combination with cooperating helically acting reducing rolls, and a driven guide disc positioned in the pass of the rolls to bear upon a blank and move in the direction of longitudinal movement of the blank through the mill; oi an articulated mandrel having a working face provided with spaced cylindrical portions of like diameter,.a smaller diameter cylindrical portion between them, and a tapered transition portion extending from each end 01' the smaller to the adjoining larger diameter portion, the man-, drel being formed of separable leading and trailing sections which are axially movable relative to each other during a tube elongating and upsetting operation, each mandrel section including one of said large diameter portions and its adjoining transition portion, whereby the forward end of an intermediate upset formed by the mill at the adjacent small diameter portion of the mandrel engages the transition portion on said leading section and causes it to move iorwardly more rapidly than said trailing section.

2. In a mill for elongating heated tubular blanks and simultaneously reducing the wall of each principally to a normal and locally to an upset thickness, the combination with cooperating helically acting reducing rolls, and a driven guide disc positioned in the pass of the rolls to bear upon a blank and move in the direction of longitudinal movement of the blank through the mill; or an articulated mandrel having a working face provided with spaced cylindrical portions of like diameter, a smaller diameter cylindrical portion between them, and a tapered transition portion extending from each end of the smaller to the adjoining larger diameter portion, the mandrel being tormed oi separable leading and trailing sections which are axially movablerelative to each other during a tube elongating and upsetting operation, each mandrel section including one of said large diameter portions and its adjoining transition portion, whereby the forward end of an intermediate upset iormedby the mill at the adjacent small diameter portion oi the mandrel engages the transition portion on said leading section and causes it to move forwardly more rapidly than said trailing section, the adjacent ends of said sections being provided with V readily separable means for aligning the sections.

3. In a mill for elongating heated tubular blanks and simultaneously-reducing the. wall 01' each principally to a normal and locally to an upset thickness, the combination with coop rating helically acting reducing rolls, and a driven guide disc positioned in the pass of the rolls to bear upon a blank and move in the direction of longitudinal movement 0! the blank through the mill; 01 an articulated mandrel having a working face provided with spaced cylindrical portions of like diameter, a smaller diameter cylindrical portion between them, and a tapered transition'portion extending from each end or the smaller to the adjoining larger diameter portion, the man- I drel being formed of separable leading and trailing sections which are axially movable relative to each other during a tube elongating and upsetting operation, each mandrel section including one of said large diameter portions and its adjoining transition portion, whereby the forward end of an intermediate upset formed by the mill at the.

' socket and the other with a pin telescopically positioned in said socket to align said sections.

4. In a mill for elongating heated tubular blanks and simultaneously-reducing the wall of each principally to a normal and locally to an upset thickness, the combination with cooperating helically acting reducing rolls, and a driven guide disc positioned in the pass of the rolls to bear upon a blank and move in the direction of longitudinal movement of the blank through the mill; or an articulated mandrel having a working face provided with spaced cylindrical portions of like diameter, a smaller diameter cylindrical portion between them, and a tapered transition portion extending from each end of the smaller to the adjoining larger diameter portion, the mandrel being formed of separable leading and trailing sections which are axially movable relative to each other during a tube elongating and upsetting operation, each mandrel section including one of said large diameter portions and its adjoining transition portion, whereby the 1orward end of an intermediate upset formed by the mill at the adjacent small diameter portion of the mandrel engages the transition portion on said leading section and causes it to move forwardly more rapidly than said'trailing section. the. rear end of said leading section being provided with a socket parallel to its axis, and the iorward'end of said trailing section being provided with a pin telescopically positioned in said socket for aligning the sections.

- SAMUEL E. DIESCI-IER. 

